Triazolo[4,5-D] pyramidine derivatives and their use as purine receptor antagonists

A compound of formula

• or a tautomer, stereoisomer, or pharmaceutically acceptable salt thereof, wherein
• R is —(CRaRb)—O—R2;
• Ra is H or alkyl;
• Rb is H or alkyl;
• or Ra and Rb together with the atom to which they are attached form a 3 to 8 membered saturated or partially saturated hydrocarbon ring or form a 4 to 8 membered saturated or partially saturated heterocylic ring comprising a ring member selected from O, N(R3) and S;
• R2 is H, alkyl, cycloalkyl or heterocycloalkyl, wherein the alkyl or cycloalkyl may optionally be substituted with halo, alkoxy or heterocycloalkyl;
• and
• R3 is H or alkyl;
• wherein:
• heteroaryl is a 5 or 6 membered aromatic ring, comprising one or two ring members selected from N, N(R4), S and O;
• alkyl (or the alkyl group of the alkoxy group) is a linear or branched saturated hydrocarbon containing up to 10 carbon atoms;
• heterocycloalkyl is a Clinked or N-linked 3 to 10 membered non-aromatic, monocyclic ring, wherein the heterocycloalkyl ring comprises 1, 2 or 3 ring members independently selected from N, N(R4), S(O)q and O;
• R4 is H or alkyl;
• and
• q is 0, 1 or 2.